<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Function dynamic_any_cast</title>
<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
<link rel="up" href="../boost_typeerasure/reference.html#doxygen.dynamic__any__cast_8hpp" title="Header &lt;boost/type_erasure/dynamic_any_cast.hpp&gt;">
<link rel="prev" href="structboost_1_1type__erasure_1_1derived.html" title="Struct template derived">
<link rel="next" href="classboost_1_1type__erasure_1_1dynamic__binding.html" title="Class template dynamic_binding">
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td>
<td align="center"><a href="../../../index.html">Home</a></td>
<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="structboost_1_1type__erasure_1_1derived.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_typeerasure/reference.html#doxygen.dynamic__any__cast_8hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="classboost_1_1type__erasure_1_1dynamic__binding.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="refentry">
<a name="doxygen.dynamic__any__cast_8hpp_1a1c580f0f07a66a57885dbb5881602cb3"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Function dynamic_any_cast</span></h2>
<p>boost::type_erasure::dynamic_any_cast</p>
</div>
<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../boost_typeerasure/reference.html#doxygen.dynamic__any__cast_8hpp" title="Header &lt;boost/type_erasure/dynamic_any_cast.hpp&gt;">boost/type_erasure/dynamic_any_cast.hpp</a>&gt;

</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> R<span class="special">,</span> <span class="keyword">typename</span> Any<span class="special">&gt;</span> <span class="identifier">R</span> <span class="identifier">dynamic_any_cast</span><span class="special">(</span><span class="identifier">Any</span> <span class="special">&amp;&amp;</span> arg<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> R<span class="special">,</span> <span class="keyword">typename</span> Any<span class="special">,</span> <span class="keyword">typename</span> Map<span class="special">&gt;</span> 
  <span class="identifier">R</span> <span class="identifier">dynamic_any_cast</span><span class="special">(</span><span class="identifier">Any</span> <span class="special">&amp;&amp;</span> arg<span class="special">,</span> <span class="keyword">const</span> <a class="link" href="structboost_1_1type__erasure_1_1static__binding.html" title="Struct template static_binding">static_binding</a><span class="special">&lt;</span> <span class="identifier">Map</span> <span class="special">&gt;</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.39.13.16.3.4"></a><h2>Description</h2>
<p>Downcasts or crosscasts an <a class="link" href="classboost_1_1type__erasure_1_1any.html" title="Class template any">any</a>.</p>
<p>


The single argument form can only be used when <code class="computeroutput">R</code> uses a single non-deduced placeholder.</p>
<p>
Example: </p>
<pre class="programlisting"><span class="comment">// Assume that typeid_&lt;&gt;, copy_constructible&lt;&gt;, and incrementable&lt;&gt;</span>
<span class="comment">// have all been registered for int.</span>
<a class="link" href="classboost_1_1type__erasure_1_1any.html" title="Class template any"><span class="identifier">any</span><span class="special">&lt;</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">typeid_</span><span class="special">&lt;</span><span class="special">&gt;</span></a><span class="special">,</span> <a class="link" href="structboost_1_1type__erasure_1_1copy__constructible.html" title="Struct template copy_constructible"><span class="identifier">copy_constructible</span><span class="special">&lt;</span><span class="special">&gt;</span></a> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">x</span><span class="special">(</span><span class="number">1</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">typedef</span> <a class="link" href="classboost_1_1type__erasure_1_1any.html" title="Class template any"><span class="identifier">any</span></a><span class="special">&lt;</span>
    <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span>
        <a class="link" href="structboost_1_1type__erasure_1_1typeid__.html" title="Struct template typeid_"><span class="identifier">typeid_</span><span class="special">&lt;</span><span class="special">&gt;</span></a><span class="special">,</span>
        <a class="link" href="structboost_1_1type__erasure_1_1copy__constructible.html" title="Struct template copy_constructible"><span class="identifier">copy_constructible</span><span class="special">&lt;</span><span class="special">&gt;</span></a><span class="special">,</span>
        <a class="link" href="structboost_1_1type__erasure_1_1incrementable.html" title="Struct template incrementable"><span class="identifier">incrementable</span><span class="special">&lt;</span><span class="special">&gt;</span></a>
    <span class="special">&gt;</span>
<span class="special">&gt;</span> <span class="identifier">incrementable_any</span><span class="special">;</span>
<span class="keyword">auto</span> <span class="identifier">y</span> <span class="special">=</span> <span class="identifier">dynamic_any_cast</span><span class="special">&lt;</span><span class="identifier">incrementable_any</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span><span class="special">;</span>
<span class="special">++</span><span class="identifier">y</span><span class="special">;</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">any_cast</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">y</span><span class="special">)</span> <span class="special">==</span> <span class="number">2</span><span class="special">)</span><span class="special">;</span>
</pre>
<p> </p>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Requires:</span></p></td>
<td><p><code class="computeroutput">R</code> and <code class="computeroutput">Any</code> must both be specializations of <a class="link" href="classboost_1_1type__erasure_1_1any.html" title="Class template any">any</a>. </p></td>
</tr>
<tr>
<td><p><span class="term">Requires:</span></p></td>
<td><p>PlaceholderMap must be an MPL map with a key for every non-deduced placeholder used by R. The value associated with each key should be the corresponding placeholder in Any. </p></td>
</tr>
<tr>
<td><p><span class="term">Requires:</span></p></td>
<td><p>The concept of Any must include <a class="link" href="structboost_1_1type__erasure_1_1typeid__.html" title="Struct template typeid_">typeid_</a>, for every <a class="link" href="structboost_1_1type__erasure_1_1placeholder.html" title="Struct placeholder">placeholder</a> which is used by R.</p></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>
<a class="link" href="classboost_1_1type__erasure_1_1bad__any__cast.html" title="Class bad_any_cast">bad_any_cast</a> if the concepts used by R were not previously registered via a call to  <a class="link" href="register__binding_8hpp_1aaea65e5d0c0b9908a16d4ebc0ef1e3ae.html" title="Function register_binding">register_binding</a>.</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<div class="copyright-footer">Copyright © 2011-2013 Steven Watanabe<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="structboost_1_1type__erasure_1_1derived.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_typeerasure/reference.html#doxygen.dynamic__any__cast_8hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="classboost_1_1type__erasure_1_1dynamic__binding.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
